1. Field of the Invention
The present invention relates to an improvement of a waterproof control unit, which is an on-vehicle electronic control device to be mounted in, for example, an engine compartment, and also relates to an improvement of a method of assembling the waterproof control unit.
2. Description of the Related Art
There have been widely used waterproof control units including a casing including a base and a cover, and a circuit board hermetically housed in the casing, onto which a circuit component and a plurality of external connection contact terminals are mounted, and a connector housing made of a resin forming material is positioned and fixed. The waterproof control units further include, in order to expose, from the casing, an end surface of the connector housing having the plurality of contact terminals passing therethrough, waterproof sealing materials filled into a first sealing gap defined between abutment surfaces of the connector housing and the cover, a second sealing gap defined between abutment surfaces of the connector housing and the base, and a third sealing gap defined between directly-opposing surfaces on respective three sides of the outer peripheries of the base and the cover, respectively. Further, as waterproof sealing surfaces, for example, there has been widely used a convexoconcave sealing surface system including convex-concave-convex threads formed in an outer peripheral contour portion of the cover, and concave-convex-concave threads formed in an outer peripheral contour portion of the base. A waterproof sealing material is filled into a convexoconcave sealing gap defined by loosely fitting the convex thread on one side into the concave thread on the other side.
The first feature of the convexoconcave sealing surface system is that a long water sealing distance (sealing path) is ensured even when the sealing width is small. The second feature of the convexoconcave sealing surface system is that, even when one convex thread wall surface abuts on one concave thread wall surface due to an assembly dimension error between the cover and the base so that the film thickness of the waterproof sealing material becomes zero, the waterproof sealing material is filled in a gap between the other convex thread wall surface and the other concave thread wall surface, and hence a predetermined amount of the waterproof sealing material is securely filled between the wall surfaces on any side.
On the other hand, a drawback of the convexoconcave sealing surface system is as follows. That is, when a fitting depth is increased with respect to a sealing width between convexoconcave sealing surfaces in order to ensure the sealing path, it is difficult for the cover and the base, which are obtained by, for example, cold pressing of an inexpensive sheet metal material, to form narrow, deep, and minute convexoconcave surfaces.
Therefore, the connector housing having a complex shape and having the contact terminals press-fitted thereinto is subjected to hot forming using a resin material, and hence can form a minute convexoconcave sealing surface. However, the connector housing having such a minute convexoconcave sealing surface cannot be used in combination with the cover and the base that are made of the inexpensive sheet metal. Thus, it is necessary to use the base and the cover formed by, for example, aluminum die casting or hot forming of a resin material.
Accordingly, in a case where there is a need to adopt the cover and the base made of the inexpensive sheet metal, there is a problem in that connector housings of different types manufactured by different dies are required.
For example, referring to FIGS. 3 and 1 of an “electronic device” disclosed in Japanese Patent Application Laid-open No. 2009-070855, a printed board 40 having a connector mounted thereonto is housed in a casing, and an inner space of the casing is waterproofed. In an upper case 20 (corresponding to the cover) and a lower case 30 (corresponding to the base) of the casing, as a sealing part that comes in contact with a sealing member, a casing-side recess part 35b is formed in one connector open edge portion, and a casing-side protruding part 25b is formed in the other connector open edge portion. At a surface portion of a housing 51 that faces the connector open edge portions, as a looped sealing part that comes in contact with the sealing member, a connector-side protruding portion 54 to be inserted into the casing-side recess part 35b under a state in which the sealing member is arranged therein and a connector-side recess portion 53 into which the casing-side protruding part 25b is to be inserted under a state in which the sealing member is arranged therein are formed continuously.
This structure is suitable for use of the cover (upper case) made of a resin and the base (lower case) formed by aluminum die casting, and the sealing surfaces of the housing 51 and the upper case 20 and the sealing surfaces of the housing 51 and the lower case 30 are arranged, in a unified manner, on a partition wall of a connector 50 into which connector terminals are press-fitted, and on an outer surface of the partition wall. There is a feature in that the widths of the protruding parts and the recess parts are limited so that a dimension corresponding to the sum of a press-fitting dimension of each of the connector terminals and a contact dimension of each of the connector terminals with those of a mating connector is minimized and thus the connector terminals do not have a long dimension.
Referring to FIG. 3 of a “board housing case for vehicle-mounted electronic device” disclosed in Japanese Patent Application Laid-open No. 2013-004611, a circuit board 40 is hermetically-sealed and housed in a metal case formed of a metal base 30 and a metal cover 20. An undulating concave thread formed in the cover 20 is fitted onto an undulating convex thread formed on a connector housing 41. The undulating convexoconcave sealing surfaces are provided on an inner side of a partition wall of the connector housing 41. An undulating convex thread formed on the base 30 is fitted into an undulating concave thread formed in the connector housing 41. The undulating convexoconcave sealing surfaces are also provided on the inner side of the partition wall of the connector housing 41.
Further, also an outline peripheral portion 23 of the cover 20 and an outline peripheral portion 33 of the base 30 form undulating convexoconcave sealing surfaces including an undulating concave thread and an undulating convex thread that are fitted to each other.
Therefore, the connector housing manufactured by the die can be used in combination with the cover made of a resin or the base formed by aluminum die casting. In this case, the outline peripheral portion 23 of the cover 20 and the outline peripheral portion 33 of the base 30 form convexoconcave sealing surfaces having a narrow width and including a deep concave thread and a tall convex thread that are fitted to each other. Thus, a contour dimension of the vehicle-mounted electronic device can be reduced.
Further, referring to FIGS. 1, 2, and 5 of “seal structure of an electronic control device” disclosed in Japanese Patent Application Laid-open No. 2013-069439, the following electronic control device is disclosed. Specifically, seal portions 50 filled with a sealing material are formed on a joining surface part between peripheral parts of a case 12 and a cover 13 of a housing, which sandwich a circuit board 11 having a connector 15 mounted on one side thereof, and formed on a joining surface part between an outer peripheral surface of the connector 15 and an inner peripheral surface of the housing. A shift suppressing unit 60 is provided to the connector 15 and, among the case 12 and the cover 13, the metal case 12 having higher rigidity than the synthetic resin cover 13. The shift suppressing unit 60 includes a protruding portion 61 and a hollow portion 62 that are fitted to each other, to thereby suppress shifting of the connector 15 with respect to the housing. With this, shifting of the connector is suppressed with respect to the housing, and the load-carrying capacity and sealing performance are enhanced.
This structure uses the resin cover 13 that is inexpensive and lightweight, and the metal case 12 that has a good heat radiating property. A first sealing gap between the cover 13 and the connector 15 is defined between a pair of flat surfaces that allows use of the cover 13 made of a sheet metal material. A third sealing gap between the cover 13 and the case 12 is formed into a sealing gap having a narrow width in such a manner that an outer peripheral bending end surface of the cover 13 is fitted into a concave thread formed in an outer periphery of the case 12.